Brain Exercises – November 21

Math Riddles

  1. What mathematical symbol can be placed between 5 and 9 to get a number greater than 5 and smaller than 9?
  2. If 6 puzzle solvers can solve 12 puzzles in 12 minutes, how long should it take a single puzzle solver to solve 60 puzzles?
  3. There are 2 numbers that total 225 and have a ratio of 2 to 13. What are the numbers?
  4. What is the number which is 5 more than one fifth of one tenth of one fourth of 1000?
  5. Fill in the missing numbers in the following series:
    101 99 102 98 103 97 ? ?
  6. When asked how old he was, Bob replied, “In 2 years I will twice as old as I was five years ago.” How old is he?
  7. If 5 cats can catch 5 mice in 5 minutes, how many cats do you need to catch 100 mice in 100 minutes?
  8. If you have a cake, how many pieces of cake can you form with 3 straight cuts?
  9. What number do you get when you multiple all the numbers on a telephone number pad?
  10. Using only addition, how do you add eight 8s and get the number 1000?

Mind Stretchers

  1. Unscramble ETCH TWO TRIPES and find a three-word preposition.
  2. Add one letter to ARISE and rearrange the rest to find a connection.
  3. Fill in each missing letter indicated by an X to make a well-known proverb TXX MOXE TXX MEXXIEX
  4. Delete one letter from BAIL and rearrange the rest to find a reason for release.
  5. Change one letter in each of these two words to form a two-word phrase: GULL GOWN
  6. What do the following words have in common? YARD WRECK MATES LOAD SHAPE OWNER WRIGHT
  7. Unscramble A TIGHTER WORD and find a three-word preposition.

Answers

Math Riddles

  1. 1.A decimal point to make it 5.9
  2. It takes a puzzle solver 6 minutes to solve a puzzle. Therefore, to solve 60 puzzles it take 360 minutes or 6 hours.
  3. 30 and 195. Think of it life this: if there is a ratio of 2 to 13, then there are 15 total parts (2 + 13). One fifteenth of 225 is 15 or one part. Two parts are 2 X 15 or 30, leaving 13 parts X 15 or 30/195=2/13
  4. 10 (1000 divided by 4 = 250 divided by 10 =25 divided by 5 =5 + 5 = 10)
  5. 104 and 96 There are really two series in one, one starts at 101 and counts up; the other starts at 99 and counts down.
  6. X + 2 = 2 (X-5) X + 2 = 2X -10 X = 12
  7. 5 cats. The same five cats could keep catching 5 mice every 5 minutes for 100 minutes.
  8. 8 pieces. Make two cuts like you normally would. Then one horizontal cut from the side of the cake.
  9. 0. All numbers multiplied by 0 equal 0.
  10. 888+ 88 + 8 + 8+ 8 = 1000

Mind Stretchers

  1. With respect to
  2. Add S and find RAISES
  3. The more the merrier
  4. Delete T and find ALIBI
  5. Dull down
  6. Each can have the prefix SHIP- to form a new word
  7. With regard to